Cerebral Protection During Cardiac Surgery

Despite many advances in perioperative care, cerebral injury from cardiac surgery remains an important source of patient morbidity and mortality. This injury has a range of clinical manifestations, including stroke and encephalopathy, which occur in 1–3% and 10–15% of patients, respectively. Postoperative cognitive dysfunction (POCD) is more common, affecting 15–40% of patients 1 month after surgery. This form of cerebral injury involves alterations in attention, concentration, and executive cognitive tasks that are detected only with detailed psychometric testing. Debate is on-going regarding whether POCD increases the risk for long-term cognitive decline and dementia, particularly in the elderly. Newman et al reported an association between POCD after CABG surgery and cognitive impairment 5 years later. In a longitudinal study, Selnes et al compared cognitive function in patients recovering from CABG surgery with that of a control group receiving medical management for coronary artery disease. Surgery and control groups showed decrements in cognition over time, but no differences in testing results were observed between the CABG surgery and the control groups 6 years after the initial evaluation. Van Dijk et al compared cognitive outcomes in patients 5 years after CABG surgery (performed with or without cardiopulmonary bypass, CPB) with a group of subjects without cardiac disease. After adjusting for differences in age, education, and co-morbidities, there was no difference in cognitive performance between CABG surgery patients and controls. Evered et al performed neuropsychological evaluations in patients undergoing total hip replacement surgery (THJR), patients undergoing CABG surgery, patients undergoing cardiac catheterization (CA), and non-procedural controls. Although the incidence of POCD at day 7 was higher in CABG surgery patients than in other patients, at 3 months the incidence of POCD was similar between groups: 21% for CA under sedation, 16% for THJR surgery, and 16% for CABG surgery (p=0.13). Accumulating data suggest that the impact of cardiac surgery on cognitive function is short lived, with recovery by 3 to 6 months after surgery in most patients. Further cognitive decline more likely results from the progression of coexisting cerebrovascular disease.